Israel hit Islamic Jihad targets in Gaza for a second day on Wednesday and Palestinian militants launched hundreds of rockets across the border, setting off sirens as far away as Tel Aviv, while Egypt began efforts to mediate an end to the fighting.
The second round of cross-border fire in a week came after Israel launched strikes on Tuesday against three Islamic Jihad commanders it said had planned attacks against Israelis, following months of escalating violence.
The Israeli military said it hit more than 130 targets, including rocket-launching sites, as blasts sounded across the Palestinian enclave.
Minutes after Wednesday's air strikes began, sirens sounded in Israel - mostly among border communities but soon also in and around the commercial capital Tel Aviv, 60 km (37 miles) north of Gaza.
More than 400 rockets were fired, Netanyahu said, a quarter of which fell short in Gaza.
The joint command of Gaza's militant groups, which includes Islamic Jihad and the enclave's Hamas rulers, claimed responsibility for the slaves.
However Israeli military officials said they had seen no signs that Hamas, which is believed to have hundreds of rockets in its arsenal, had fired any missiles itself.
They said Israeli strikes were directed only at targets linked to the smaller Islamic Jihad group, an Iranian-backed militant organization based in Gaza which has been increasingly active in the occupied West Bank for the past year.
In total, 24 Palestinians, including at least five women and five children, as well as three senior Islamic Jihad commanders and four gunmen have been killed since fighting began, Palestinian health officials said.
The militant groups said the rocket salvoes were a retaliation for the Israeli strikes, which it described as "a savage and treacherous bombardment of civilian houses that led to several innocent martyrs."
Reuters